From April 1995 to April 1996, the annual reproductive cycle of the Eurasian perch Perca fluviatilis was studied at the Fishfarming Lindre Center (Moselle, France). At monthly intervals (at intervals of 10 days during the periovulatory period), 5 females were caught and dissected. From sampled organs, the gonado-, hepato- and viscerosomatic indexes (GSI, HSI, VSI) were calculated, oocyte diameters (OD) and the plasma levels of testosterone (T), 17β-estradiol (E 2 ), 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P) and protein-phosphorus (PPP) were measured. After the sexual resting period observed from May to August (GSI < 1 %, OD < 200 μm, VSI = 4-6 %), oogenesis began in September when the water temperature decreased from 26.4 to 14.1 °C. The GSI increased progressively until mid March (15 %), then rapidly until spawning (25 %, OD = 850 μm) which occurred in April (14-15 °C). The plasma levels of T, E 2 , 17,20β-P and PPP were low during the sexual resting period. E 2 and PPP levels increased significantly at the onset of the oogenesis in September, then the E 2 level raised abruptly in November (3-4 ng mL - 1 ). In December, the T level increased rapidly to 15-20 ng mL - 1 . The testosterone, E 2 and PPP levels remained very high until spawning, indicating the existence of active vitellogenesis. The highest HSI (2.1-2.2 %) recorded in winter confirmed this. During the periovulatory period, a peak of E 2 (4 ng mL - 1 ) appeared, whereas T level diminished. In this study, 17,20β-P levels remained low (0.2-0.6 ng mL - 1 ) and relatively constant. No 17,20β-P peak was observed during the periovulatory period. Sampling at 10 day intervals was probably inadequate to specify the hormonal variations related to the final oocyte maturation and the ovulation.Entre avril 1995 et avril 1996, une etude a ete conduite au Centre Piscicole Departemental du Domaine de Lindre (Moselle, France) pour etudier le cycle annuel de reproduction de la perche eurasienne Perca fluviatilis. Celle-ci s'appuie sur des captures mensuelles (ou tous les 10 jours en periode peri-ovulatoire) de 5 femelles, sur lesquelles le prelevement d'organes a permis le calcul des indices gonado-, hepato- et viscero-somatique (IGS, IHS, IVS), la mesure du diametre ovocytaire (DO) et le dosage des teneurs, dans le plasma, en testosterone (T), 17β-estradiol (E 2 ), 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P) et phosphore proteique (PPP). Apres la phase de repos sexuel observee de mai a aout (IGS < 1 %, DO < 200 μm, IVS = 4-6 %), l'ovogenese debute en septembre lorsque la temperature de l'eau diminue de 26,4 a 14,1 °C. Des lors, l'IGS augmente progressivement jusqu'a la mi-mars (15 %), puis fortement jusqu'a la ponte (25 %, DO = 850 μm), qui intervient en avril (14-15 °C). Les teneurs en T, E 2 , 17,20β-P et PPP sont faibles pendant la phase de repos sexuel. Les taux de E 2 et de PPP augmentent significativement avec le debut de l'ovogenese en septembre, puis la teneur en E 2 s'eleve fortement en novembre (3-4 ng mL - 1 ). En decembre, la concentration en T atteint rapidement des valeurs de 15-20 ng mL - 1 . Les taux de T, E 2 et PPP restent tres eleves jusqu'a la periode de ponte ce qui indique le maintien d'une vitellogenese active. Le calcul de l'IHS (2,1-2,2 %) plus eleve pour la periode hivernale le confirme. Pendant la periode peri-ovulatoire, un pic de E 2 (4 ng mL - 1 ) survient, alors que T diminue. Au cours de cette etude, les teneurs en 17,20β-P restent faibles (0,2-0,6 ng mL - 1 ) et relativement constantes. Aucun pic de 17,20β-P n'a ete observe pendant la periode peri-oovulatoire. Un echantillonnage tous les 10 jours s'avere insuffisant pour preciser les fluctuations hormonales liees a la maturation ovocytaire finale et a l'ovulation.